This invention relates to borescopes or endoscopes of the type in which a miniature video camera is mounted at a distal viewing head of an elongated insertion tube. The invention is more particularly concerned with an improved laparoscope in which illumination for the miniature video camera is supplied from a low-wattage but high-efficiency lamp and thence through a light conduit to the tip of the laparoscope probe tube.
Recently, interest has increased in the use of video instruments for surgical applications to permit a surgeon to carry out a procedure with minimal intervention in the patient. An example of one such video instrument is a laparoscope for performing surgery in the abdominal cavity, where the instrument is inserted through a small incision. Other probes are provided for diagnosis of medical conditions in the colon or in the gastro-enteric tract. Small probes can also be used in eye surgery. Further examples are found in industrial probes, i.e., borescopes, for inspection of equipment such as boilers or steam generators, or jet engine rotors where non-destructive penetration of the equipment is necessary. In each case the tissues or parts to be investigated may be quite sensitive to heat; thus if infrared or heat is produced with the light from the instrument's light box, inspection can injure or damage the target.
It is also desirable for laparoscopes to operate at low power consumption rates, for example, so that the unit can be constructed compactly and of light weight, and also so that the laparoscope can be made battery powered and portable, e.g. for veterinary purposes.
However, until now suitable illumination was possible only with high wattage, high pressure xenon arc lamps. These produce a large amount of waste heat and their energy can not be focussed down onto a small spot to enter the fiber optic bundle or other light conduit.
A number of full-color video probes of this general type have been described, for example, in Danna et al. U.S. Pat. No. 4,491,865, Danna et al. U.S. Pat. No. 4,539,586, and Longacre et al. U.S. Pat. No. 4,523,224.